The present invention relates generally to the field of telecommunication networks, and more particularly to a method and system for transporting traffic in a packet-switched network.
Telecommunication networks transport voice and data according to a variety of standards and using a variety of technologies. Circuit-switch networks such as plain old telephone service (POTS) utilize transmission paths dedicated to specific users for the duration of a call and employ continuous, fixed-bandwidth transmission. Packet-switch networks (PSNs) allow dynamic bandwidth, depending on the application, and can be divided into connectionless networks with no dedicated paths and connection-oriented networks with virtual circuits having dedicated bandwidth along a predetermined path. Because packet-switched networks allow traffic from multiple users to share communication links, these networks utilize available bandwidth more efficiently than circuit-switched networks.
Internet protocol (IP) networks are connectionless packet-switched networks. IP networks transport information by breaking up bitstreams into addressable digital packets. Each IP packet includes source and destination addresses and can take any available route between the source and the destination. The IP packets are transmitted independently and then reassembled in the correct sequence at the destination.
Conventional IP networks employ routers to direct packets to their destination. Packets are inspected at each router for network protocol addresses and forwarded to a next router on the way toward the destination based on downstream congestion and other real-time parameters. While this inspection and dynamic routing provides a high degree of flexibility within the network, it adds delays to each packet at each router. Accordingly, traffic transported across an IP network between geographically distributed source and destination points will have a relatively large cumulative delay. This limits the ability of the IP network to support voice, video, and other real-time applications.
The present invention provides an improved method and system for transporting traffic in a packet-switched network that substantially eliminate or reduce the problems and disadvantages associated with previous systems and methods. In particular, the present invention provides a packet-switched network with high-speed links between geographically distributed nodes. The nodes are directionally-sensitive to direct traffic with minimal delays and support voice, video and other real-time applications.
In accordance with one embodiment of the present invention, a method and system for processing traffic in a network node includes segmenting high priority pass-through traffic from low priority pass-through traffic. The high priority pass-through traffic is transmitted on an egress link preferentially over the low priority pass-through traffic and ingress high priority local traffic. The ingress high priority local traffic is transmitted on the egress link preferentially over the low priority pass-through traffic.
More specifically, in accordance with a particular embodiment of the present invention, the traffic may comprise Internet Protocol (IP) packets. In this and other embodiments, the high priority traffic may be reserved bandwidth traffic and the local priority traffic may be reserved bandwidth traffic and the local priority may be unreserved bandwidth traffic. The high and low priority IP packets may be segmented based on their quality of service (QoS).
In accordance with another aspect of the present invention, a node for a telecommunications network includes a high-speed ingress link, a high-speed egress link and a local interface. A directionally-sensitive interface is coupled between the high-speed ingress link, the high-speed ingress link and the local interface. The directionally-sensitive interface is operable to receive an ingress traffic stream on the high-speed link, to segment high priority pass-through traffic from low priority pass-through traffic in the ingress traffic stream, to transmit on the high-speed ingress link the high priority pass-through traffic preferentially over the low priority pass-through traffic and ingress high priority local traffic received from the local interface, and to transmit on the egress link the ingress high priority local traffic preferentially over the low priority pass-through traffic.
In accordance with still another aspect of the present invention, a telecommunications network includes a plurality of nodes interconnected by links. A path is defined through the network between the a source node and the destination node. The path includes dedicated links from the source node through intermediate nodes to the destination node in directionally-sensitive interfaces at each intermediate node. The directionally-sensitive interfaces are each operable to segment high and low priority pass-through traffic and to transmit the high priority pass-through traffic on the path preferentially over the low priority pass-through traffic and the local traffic.
Technical advantages of the present invention include providing an improved packet-switched network. In particular, the packet-switched network provides high-speed links between directionally-sensitive network nodes. Fast paths are defined through the nodes to transport traffic with no substantial node delay. This allows queuing delays to be accurately estimated and increases bandwidth manageability for reserved traffic. In addition, the low-latency links allows voice, video, and other real-time traffic to be supported by the packet-switched network.
Another technical advantage of the present invention includes providing class of service (CoS) support for Internet protocol (IP) traffic. In particular, traffic is distinguished and routed based on its CoS parameters. This allows high-priority traffic to be processed with minimal delay across a number of nodes and low-priority traffic to be delayed or dropped to avoid down-stream starvation.
Still another technical advantage of the present invention includes providing an improved method and system for transporting traffic in a packet-switched network. In particular, all high priority or reserve traffic on a fast path is passed through a node using only shallow look-up while low priority or unreserved traffic is buffered to prevent node starvation. Local high priority reserve traffic is added to the egress traffic stream based on bandwidth availability. Local and pass-through low priority traffic is added based on remaining bandwidth availability.
Still another technical advantage of the present invention includes providing an improved IP node for processing traffic in an IP network. In particular, the node is an add-drop multiplexer (ADM) with directionally-sensitive traffic processing functionality that processes through traffic with substantially no node delay. In addition to reducing delay, the sense of direction reduces buffer speed and allows for more accurate connection admission control (CAC), which reduce cost of the node while improving operational efficiency.
Other technical advantages of the present invention will be readily apparent to one skilled in the art from the following figures, description, and claims.